Collapsible substructure for a mobile drilling rig

Abstract

Generally, the present disclosure is directed to a collapsible substructure of a mobile drilling rig. In one illustrative embodiment, a drilling rig substructure is disclosed that includes a base having a fixed drill floor mounted thereon, wherein an upper surface of the fixed drill floor is positioned at an operating height above the base for performing drilling operations at a wellbore location of a drilling site. Furthermore, a raisable floor is also included that is adapted to be positioned in a lowered transportation position for transportation of the substructure to the drilling site and raised to an operating position adjacent to the fixed drill floor for performing drilling operations, wherein a height level of an upper surface of the raisable floor is lower than a height level of the upper surface of the fixed drill floor when the raisable floor is positioned in the lowered transportation position.

What is claimed: 
     
       1. A drilling rig substructure, comprising:
 a base; 
 a fixed drill floor mounted on said base, wherein an upper surface of said fixed drill floor is adapted to be positioned at an operating height level that is a same first distance above said base during both transportation of said drilling rig substructure to a drilling site and while performing drilling operations at a wellbore location of said drilling site; and 
 a raisable floor that is adapted to be positioned in a lowered transportation position during said transportation of said drilling rig substructure to said drilling site and raised from said lowered transportation position to an operating position adjacent to said fixed drill floor for performing said drilling operations, wherein an upper surface of said raisable floor is adapted to be positioned at a transportation height level that is a second distance above said base when said raisable floor is positioned in said lowered transportation position, said second distance being less than said first distance, and wherein a plane defined by said upper surface of said raisable floor is adapted to be substantially parallel to a plane defined by said upper surface of said fixed drill floor when said raisable floor is in said lowered transportation position during said transportation of said drilling rig substructure to said drilling site and when said raisable floor is in said raised operating position during said drilling operations. 
 
     
     
       2. The drilling rig substructure of  claim 1 , wherein at least one side of said drilling rig substructure is adapted to be substantially open after said raisable floor has been raised to said operating position, said drilling rig substructure being adapted to be moved in a substantially horizontal direction over wellhead equipment that is positioned on a wellhead at said wellbore location after said raisable floor has been raised to said operating position such that at least a portion of said wellhead equipment passes laterally through said at least one substantially open side during said substantially horizontal movement of said drilling rig substructure over said wellhead equipment. 
     
     
       3. The drilling rig substructure of  claim 1 , wherein said raisable floor is further adapted to raise a drawworks substantially to said operating height level of said fixed drill floor and support said drawworks during said drilling operations. 
     
     
       4. The drilling rig substructure of  claim 1 , further comprising a raising apparatus that is adapted to raise and lower said raisable floor. 
     
     
       5. The drilling rig substructure of  claim 4 , wherein said raising apparatus comprises at least one raising device that is pivotably connected to at least said raisable floor. 
     
     
       6. The drilling rig substructure of  claim 5 , wherein said at least one raising device comprises a hydraulic cylinder apparatus. 
     
     
       7. The drilling rig substructure of  claim 4 , wherein said raising apparatus comprises a plurality of pinned structural members that are each pivotably connected to at least said raisable floor, said plurality of pinned structural members being adapted to laterally move said raisable floor into said operating position adjacent to said fixed drill floor. 
     
     
       8. The drilling rig substructure of  claim 1 , further comprising a locking apparatus that is adapted to lock said raisable floor in place adjacent to said fixed drill floor after said raisable floor has been raised to said operating position. 
     
     
       9. The drilling rig substructure of  claim 1 , wherein said base comprises one or more bearing pad support beams that are adapted to be in bearing contact with at least one of ground adjacent to said wellbore location and a drilling mat positioned on said ground so as to provide bearing support of said drilling rig substructure during said drilling operations, each of said one or more bearing pad support beams being further adapted to be raised relative to said fixed drill floor and said raisable floor to a movement position such that said base is positioned a third distance below said upper surface of said fixed drill floor and maintained in said movement position while said drilling rig substructure is moved from said wellbore location of said drilling site to a second wellbore location of said drilling site, said third distance being less than said first distance. 
     
     
       10. The drilling rig substructure of  claim 1 , wherein said raisable floor is adapted to be lowered from said operating position to an intermediate movement position that is above said lowered transportation position and below said operating position and maintained in said intermediate movement position while said drilling rig substructure is moved from said wellbore location of said drilling site to a second wellbore location of said drilling site. 
     
     
       11. The drilling rig substructure of  claim 1 , wherein said drilling rig substructure is adapted to be releasably coupled to a drilling rig mast assembly comprising a drilling mast, said drilling rig substructure being further adapted to support said drilling mast during said drilling operations. 
     
     
       12. The drilling rig substructure of  claim 1 , wherein said raisable floor is adapted to be coupled to said base during transportation of said drilling rig substructure to said drilling site. 
     
     
       13. A substructure of a drilling rig that is adapted to be moved between a plurality of wellbore locations of a drilling site, the substructure comprising:
 a base that is adapted to provide bearing support of said substructure during drilling operations at each of said plurality of wellbore locations; 
 a fixed drill floor mounted on said base, wherein said fixed drill floor is adapted to be positioned at a first height level relative to said base during transportation of said substructure to said drilling site, said fixed drill floor being further adapted to be positioned at said same first height level relative to said base during said drilling operations; 
 a raisable floor coupled to said base, wherein said raisable floor is adapted to be positioned at a second height level relative to said base during said transportation, said second height level being less than said first height level; and 
 a raising apparatus that is adapted to raise said raisable floor above said base from said position at said second height level to a drilling operation position adjacent to said fixed drill floor, said raising apparatus being further adapted to raise said base relative to said fixed drill floor so that said fixed drill floor is at a third height level relative to said base and to maintain said base in said raised position during said movement of said substructure between said plurality of wellbore locations, wherein said third height level is less than said first height level. 
 
     
     
       14. The substructure of  claim 13 , wherein said substructure is adapted to be moved between said plurality of wellbore locations while said raisable floor is in said drilling operation position. 
     
     
       15. The substructure of  claim 14 , wherein said substructure is adapted to be moved in a substantially horizontal direction over wellhead equipment that is positioned on a wellhead of at least one of said plurality of wellbore locations so that said wellhead equipment passes laterally through a cellar area of said substructure below said fixed drill floor. 
     
     
       16. The substructure of  claim 15 , wherein at least one side of said substructure is adapted to be substantially open when said raisable floor is in said drilling operation position, said at least one substantially open side being adapted to allow said wellhead equipment to pass laterally therethrough. 
     
     
       17. A drilling rig substructure, comprising:
 a base; 
 a raisable floor coupled to said base, wherein said raisable floor is adapted to be positioned in a lowered transportation position that is at a first height level above said base during transportation of said drilling rig substructure to a drilling site; 
 a fixed drill floor mounted on said base, said fixed drill floor being positioned at a second height level above said base that is greater than said first height level during said transportation of said substructure to said drilling site and while performing drilling operations at a first wellbore location of said drilling site, wherein said raisable floor is further adapted to be raised relative to said base and said fixed drill floor to a raised operating position adjacent to said fixed drill floor that is at a third height level above said base and maintained in said raised operating position while performing said drilling operations, and wherein a plane defined by an upper surface of said raisable floor is adapted to be substantially parallel to a plane defined by an upper surface of said fixed drill floor when said raisable floor is in said lowered transportation position during said transportation of said substructure to said drilling site and when said raisable floor is in said raised operating position while performing said drilling operations at said first wellbore location of said drilling site. 
 
     
     
       18. The drilling rig substructure of  claim 17 , further comprising a raising apparatus that is adapted to raise said raisable floor above said base from said first height level of said lowered transportation position to said second height level of said raised operating position adjacent to said fixed drill floor. 
     
     
       19. The drilling rig substructure of  claim 18 , wherein said base is adapted to contact at least one drilling mat positioned adjacent to said first wellbore location and to support said drilling rig substructure during said drilling operations, said raising apparatus being further adapted to raise said base relative to said fixed drill floor and said raisable floor to a raised movement position and to maintain said base in said raised movement position during movement of said drilling rig substructure from said first wellbore location to a second wellbore location of said drilling site, wherein said fixed drill floor is at a fourth height level above said base that is less than said second height level when said base is in said raised movement position. 
     
     
       20. The drilling rig substructure of  claim 17 , wherein said drilling rig substructure is adapted to be moved between said first wellbore location and a second wellbore location of said drilling site while said raisable floor is maintained in said raised operating position. 
     
     
       21. The drilling rig substructure of  claim 17 , wherein said raisable floor is further adapted to be lowered from said raised operating position to an intermediate movement position that is at a fourth height level above said base and maintained in said intermediate movement position while said drilling rig substructure is moved from said first wellbore location to a second wellbore location of said drilling site, said fourth height level being greater than said first height level and less than said second height level. 
     
     
       22. The drilling rig substructure of  claim 17 , wherein said drilling rig substructure is adapted to be moved in a substantially horizontal direction over wellhead equipment that is positioned on a wellhead of said first wellbore location so that said wellhead equipment passes laterally through a cellar area of said drilling rig substructure below said fixed drill floor. 
     
     
       23. The drilling rig substructure of  claim 22 , wherein at least one side of said drilling rig substructure is adapted to be substantially open when said drilling rig substructure is moved in said substantially horizontal direction over said wellhead equipment, said at least one substantially open side being adapted to allow said wellhead equipment to pass laterally therethrough. 
     
     
       24. The drilling rig substructure of  claim 17 , wherein said raisable floor is adapted to be coupled to said base during transportation of said drilling rig substructure to said drilling site. 
     
     
       25. A drilling rig substructure, comprising:
 a base; 
 a fixed drill floor mounted on said base, wherein an upper surface of said fixed drill floor is adapted to be positioned at an operating height level that is a same first distance above said base during both transportation of said drilling rig substructure to a drilling site and while performing drilling operations at a wellbore location of said drilling site; and 
 a raisable floor that is adapted to be positioned in a lowered transportation position during said transportation of said drilling rig substructure to said drilling site and raised from said lowered transportation position to an operating position adjacent to said fixed drill floor for performing said drilling operations, wherein an upper surface of said raisable floor is adapted to be positioned at a transportation height level that is a second distance above said base that is less than said first distance when said raisable floor is positioned in said lowered transportation position, and wherein at least one side of said drilling rig substructure is adapted to be substantially open after said raisable floor has been raised to said operating position, said drilling rig substructure being adapted to be moved in a substantially horizontal direction over wellhead equipment that is positioned on a wellhead at said wellbore location after said raisable floor has been raised to said operating position such that at least a portion of said wellhead equipment passes laterally through said at least one substantially open side during said substantially horizontal movement of said drilling rig substructure over said wellhead equipment. 
 
     
     
       26. A drilling rig substructure, comprising:
 a base comprising one or more bearing pad support beams, said one or more bearing pad support beams being adapted to be in bearing contact with at least one of ground adjacent to a wellbore location of a drilling site and a drilling mat positioned on said ground so as to provide bearing support of said drilling rig substructure during drilling operations; 
 a fixed drill floor mounted on said base, wherein an upper surface of said fixed drill floor is adapted to be positioned at an operating height level that is a same first distance above said base during both transportation of said drilling rig substructure to said drilling site and while performing drilling operations at said wellbore location of said drilling site; and 
 a raisable floor that is adapted to be positioned in a lowered transportation position during said transportation of said drilling rig substructure to said drilling site and raised from said lowered transportation position to an operating position adjacent to said fixed drill floor for performing said drilling operations, wherein an upper surface of said raisable floor is adapted to be positioned at a transportation height level that is a second distance above said base that is less than said first distance, when said raisable floor is positioned in said lowered transportation position, and wherein each of said one or more bearing pad support beams is further adapted to be raised relative to said fixed drill floor and said raisable floor to a movement position such that said base is positioned a third distance below said upper surface of said fixed drill floor that is less than said first distance and maintained in said movement position while said drilling rig substructure is moved from said wellbore location of said drilling site to a second wellbore location of said drilling site.